关键词: 高寒草甸, 放牧强度, 土壤因子, 群落特征

Abstract: Conventional rice Xiangzaoxian 45 was used as test material, and waterlogged at different submergence depths (two-thirds submerged and fully submerged) for variable durations (3, 5, 7, and 9 days) at the jointing stage to investigate the influence of waterlogging stress on green leaf’s number, curly leaf’s length, leaf sheath’s length, high tillering and other morphological factors and yield components. Results showed that, in the different submergence depth treatments, the green leaf’s number had a negative correlation with the flooding time, and two-thirds of submergence had a more obvious effect than full submergence. Stems changed obviously in the full submergence treatment, while leaves changed significantly in the two-thirds of submergence. High tillering rate had a positive correlation with the flooding time. Curl leaf’s length had a negative correlation with the flooding time under the two-thirds of submergence, but a positive correlation under full submergence. Leaf sheaths among different treatments, all showing the elongation growth, were not significantly different. The different submergence stresses all increased the unfulfilled grain rate and empty grain rate, and lowered the thousandgrain weight. The treatment of two-thirds of submergence for 9 days had the severest effect, with lowest grain number (34). We discussed the adaptation mechanisms and possible causes for stems, leaves and other morphological characteristics under the different submergence stresses. The results could provide a scientific basis for flooding disaster reduction and disasterresistant breeding of rice for the middle and lower reaches of Yangtze River.

Key words: alpine meadow, grazing intensity, community characteristics, soil factor